Photodiodes have been configured in many ways and use many different materials for absorbing light energy over different wavelengths to generate photocurrent or voltage depending upon the mode. Temperature affects dark current as higher temperature increases dark current and degrades the noise equivalent sensitivity of the device. To achieve increased sensitivity, temperature is typically reduced. To reduce temperature, however, more power is needed to cool the detector. In addition, the cooling systems are necessarily larger and more expensive.
High density vertically integrated photodiode (HDVIP®, a trademark of DRS Technologies, Inc.) architecture has been employed to form pixels in focal plane arrays (FPAs) used for an infrared radiation detection. Photodiodes formed in prior art HDVIP® infrared detectors typically are formed from a single homogenous semiconductor layer of Mercury Cadmium Telluride (“HgCdTe”) to have a given wavelength cutoff. Such prior art infrared detectors employing photodiodes formed of HgCdTe are susceptible to noise due to thermally excited current carriers and dark current sources at high operating temperatures and, thus, require substantial cooling to reduce the operating temperature of the detector so as to correspondingly reduce the noise and dark current of the detector.
Therefore, there has always been a need for an infrared radiation detectors that operate at higher temperatures without degradation in performance.